1. Field of the Invention
The present invention relates to a radar head module such as a vehicle-mounted EHF (extremely high frequency) radar and a characteristic adjustment method thereof.
2. Description of the Related Art
Japanese PCT Patent Publication No. 2000-508874 discloses microwave and millimeter-wave radars suitable for being vehicle-mounted. In a radar head module shown in this Publication, in order to effectively utilize a space between a primary radiator and a dielectric lens, a circuit board is arranged between the primary radiator and the dielectric lens and a notch for passing electromagnetic waves is formed on the circuit board.
However, in the radar head module shown in the Publication, a rectangular circuit board used generally is difficult to be utilized, thereby increasing cost. Since the circuit board is arranged on the back bottom of a box-like case, efficiency of assembling is low and manufacturing cost is increased. Furthermore, since the circuit board is attached to the case, the module cannot be operated as a radar head in a state in which the case is removed, so that characteristics of the radar head module cannot be absolutely adjusted in a state in which the case of the radar head module is attached at a predetermined position of a vehicle with the case removed.